1. Field of the Invention
The present invention relates to semiconductor processing furnaces, and more particularly, pertains to an atmospheric door closure for sealing against a process tube orifice.
2. Description of the Prior Art
Prior art clamping mechanisms have not been reliable and have caused particulate contamination. Prior art sealing devices have introduced varying degrees of particulate contamination and have provided for increased back-streaming of room atmospheric gases into the wafer process chamber. Past prior art systems have usually supported a door on a single spring biased rod. The spring would tend to relax after being exposed to heat. When the springs relaxed, the door would not seal. Also, the single rod would not provide for concentricity between the door and the paddle. When the springs oxidized, particles would be released and would migrate into the process tube. The prior art doors also had large holes and the doors would sometimes touch the paddle. The prior art systems provided little if any adjustment, a single support, and a hole in a single door.
The present invention provides an atmospheric door closure for assurance of reliability and increased wafer loads with high yields.